1. Field of the Invention
The present invention relates to a torque transmission device and a method of reducing effects of torque pulsations, and in particular to a torque transmission device that transmits the torque of an internal combustion engine to a drive shaft and a method of reducing, using the torque of a motor generator, the effects, on a drive shaft, of torque pulsations generated in the torque from an internal combustion engine when the torque from the internal combustion engine is transmitted to the drive shaft.
2. Description of the Related Art
Conventionally, a hybrid drive device has been known as a drive device having an internal combustion engine and an electric motor. This kind of hybrid drive device has come to be used as a drive device in vehicles in order to reduce exhaust gas and improve fuel consumption.
The conventional hybrid drive device is equipped with an engine, such as an internal combustion engine, that operates by burning fuel, a spring-type damper device that absorbs the rotational movement of the engine, a planetary gear-type distribution mechanism that mechanically distributes, to a first motor generator and an output member, the output of the engine transmitted via the damper device, and a second motor generator that applies a rotational force to the output member (Japanese Patent Application Laid-Open (JP-A) No. 9-170533).
When the first motor generator is switched to an unloaded state and reversely rotated at the time a vehicle using only the second motor generator as a source of power is traveling, the hybrid drive device can rotatingly drive and start the engine via the distribution mechanism by causing the first motor generator to generate a predetermined braking torque or a predetermined torque in a positive rotational direction. In that case, because part of the output of the second motor generator is consumed by the rotation of the engine, the second motor is operated by an output equal to or greater than the power necessary for travel and the engine is rotatingly driven by the additional power equal to or greater than the necessary power—i.e., by a power in which the necessary power is subtracted from the output of the second motor generator. Thus, fluctuations in drive power resulting from the starting of the engine can be suppressed.